In recent years, disk drives, such as magnetic disk drives, optical disc drives, etc., have become widely used as external recording devices of computers or image or music recording/reproducing apparatuses.
A hard disk drive (HDD), for example, generally comprises a magnetic disk, spindle motor, head actuator, voice coil motor, circuit board unit, etc. The spindle motor supports and rotates the disk disposed in a housing. The head actuator supports a magnetic head. The voice coil motor drives the head actuator.
The housing comprises an open-topped base mounted with a plurality of mechanisms and a top cover that closes the opening of the base. The top cover is attached to the peripheral edge portion of the top surface of the base by screws. A bearing portion of the head actuator comprises a pivot, which stands on the base with its distal end attached to the top cover by a screw. Thus, the pivot is doubly supported in the housing.
In the magnetic disk drive constructed in this manner, vibration is produced as the spindle motor and magnetic disk rotate, the head actuator is caused to vibrate by an air current attributable to the disk rotation, and vibration is produced by a seek operation of the head actuator. Vibrations of the spindle motor and head actuator, as vibrating elements, are transmitted to the plate-like top cover through the base, the pivot of the head actuator, etc. Thus, the top cover vibrates and produces noise.
Accordingly, an apparatus is proposed in which the top cover is formed with ribs or constrictions for improved mechanical strength. In an apparatus described in Jpn. Pat. Appln. KOKAI Publication No. 2004-46964, for example, the top cover is formed with arcuate ribs or constrictions concentric with a disk. In another apparatus described in Jpn. Pat. Appln. KOKAI Publication No. 2006-331545, an opening is formed in that part of the top cover which is located just above yokes.
Modern information processing apparatuses, however, are required to be smaller and thinner, so that there is an increasing demand for thinner magnetic disk drives to be used in these apparatuses. Therefore, the top cover of the disk drives may be too thin to be sufficiently rigid. Further, secondary vibration, as well as primary vibration, of the top cover may cause a noise problem.